Activity of glutamate and IVM at homo- and heteromeric GluClRs.

A. Structure of the GluClR (3RIF, [5]) showing the large extracellular domain with glutamate bound at interfaces between adjacent subunits. Also shown is the transmembrane domain, which consists of four helices (M1-M1) per subunit and IVM bound between the M1 and M3 of adjacent subunits. B. Sequence alignments of selected invertebrate GluClRs subunits showing the IVM binding site, which consists of the first (M1) to third (M3) transmembrane domains. Boxed in red are sites of missense mutations that reduce IVM sensitivity. Abbreviations are H. cont., H. contortus, C. eleg., C elegans, P. xylos., P. xylostella, T. urtic., T. urticae (isoforms 1 and 3) and D. melan., D. melanogaster. C. Example currents obtained in oocytes injected with the β subunit (above) or the α and β subunits (ratio 1:50, below) in response to the indicated glutamate concentrations. D. Group concentration-response data for the indicated GluClRs. Holding potential was –40 mV.